Various medical procedures involve accessing a chamber of the heart using a trans-septal approach. For example, a guide catheter or sheath may be introduced into the right atrium of a patient's heart, e.g., from a percutaneous access site, and a Brockenbrough needle may be introduced through the guide sheath and advanced through the intra-atrial septum of the heart into the left atrium. A guidewire may be then introduced through the needle into the left atrium, whereupon the needle may be removed.
One or more dilators may be advanced over the guidewire (or over the needle before removal) to dilate the puncture through the septum, e.g., to create a passage sufficiently large to introduce the guide sheath through the puncture in the septum. The dilator provides a transition to bridge the diameter difference between the guidewire and the outer diameter of the guide sheath. The taper provided on the tip of such dilators is generally a substantially uniform conical ramp, and the longer the taper (i.e., the more shallow the angle), the lower the axially-applied axial force needed to apply the same radial dilation force against the tissue surrounding the puncture.
However, if the length of dilator tip is too long, it may present a safety risk, such as left atrial perforation or other damage to tissue. For example, a dilator taper may be too long for a number of reasons including 1) it is so long that it touches undesired anatomy before the guide sheath can access the desired space (e.g., the left atrial wall, vessel bifurcation, and the like) or 2) in the follow-through that frequently happens (e.g., when the insertion force drops dramatically when fully dilated to the sheath diameter) the dilator tip may touch and/or damage undesired anatomy.
One or more instruments may then be introduced through the guide sheath and/or over the guidewire into the left atrium, e.g., to perform a procedure within the left atrium or other region of the heart accessed via the left atrium.
Additionally, there is a need for devices that facilitate accessing body lumens, such as chambers of the heart using trans-apical approaches and/or other puncture techniques, e.g., to perform medical procedures therein, while reducing the risk of undesired punctures or tissue damage.